Seeking advice on some issues regarding the utility systems in the fractionation tower of FCCU
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This post was last edited by pekingcedar on 2010-1-19 at 15:06. In the drawings, I saw that the utility for the circulation in the distillation column of the FCCU is circulating water cooling； The utility systems for the top loop are low-temperature warm water, desalinated water, and circulating water ； The utility systems for condensation at the tower top are demineralized water, air cooling, and circulating water cooling ； I’m not very familiar with utility systems, so I’d like to ask everyone a few questions: Are circulating water, demineralized water, and low-temperature warm water all sources of energy consumption for a factory? Is there no possibility of using this heated water for other purposes? Also, I’ve read many studies that suggest increasing the circulation flow rates in Unit 1 and Unit 2 as much as possible within the limits imposed by operational conditions, in order to enhance external heat extraction. But if the heat absorbed by the heat exchangers in Unit 1 and Unit 2 remains relatively constant – for example, if the bottom temperatures of the stabilizer tower and the desorber tower do not change – then wouldn’t the additional heat generated require more utility energy for cooling? Won’t that result in higher power consumption? I’m not very familiar with the site conditions or the utility systems, so my questions might not be very professional. I appreciate your guidance; thank you~
Circulating water, demineralized water, and low-temperature warm water each have their own uses. Circulating water is mostly used for cooling; its losses occur due to leaks and water evaporation. The amount of circulating water required is directly related to energy consumption, as a greater volume requires more cooling infrastructure, thus its energy use needs to be considered from various perspectives； Demineralized water has many uses in factories; the deoxygenated water used there is obtained from it, and deoxygenated water is primarily used for generating steam ； Low-temperature warm water is what we refer to as low-temperature heat. In factories, when the temperature drops below a certain level, it becomes difficult to find ways to recover this heat, resulting in waste of energy; this heat is known as low-temperature heat. Low-temperature water usually enters at around 70°C, and every effort should be made to recover this heat for use in other purposes, such as heating. Regarding the question below, I think it’s not expressed very clearly. As you said, it seems to involve a waste of cooling utility resources. However, the distillation tower also has its own operating conditions, such as temperature and the heat extraction load for each section. Although these values can’t be set fixedly, their total amount is determined. It’s acceptable for the distillation tower to draw an appropriate amount of heat, but this depends on the quality of the product. Also, cooling utility resources aren’t all the same as circulating water; low-temperature hot water or combined heat systems can be used, among other options. These are just my personal opinions; please feel free to point out any mistakes